It is an object of the invention to provide fertilizer compositions which release the fertilizer components a controlled rate. More particularly, it is an object of the invention to provide water-in-oil emulsion fertilizer compositions with controlled release properties.
Water-in-oil emulsions have been used for a variety of uses including emulsion explosives. Water-in-oil explosive emulsions typically comprise a continuous organic phase and a discontinuous oxidizer phase containing water and an oxygen-supplying source such as ammonium nitrate, the oxidizer phase being dispersed throughout the continuous organic phase. Examples of such water-in-oil explosive emulsions are disclosed, inter alia, in U.S. Pat. Nos. 5,047,175; and 4,828,633. The emulsifier is a salt derived from high molecular weight carboxylic acylating agent coupled to a low molecular weight carboxylic acylating agent. Succinic acids and anhydrides are the preferred acylating agents.
U.S. Pat. No. 4,919,178 discloses water in oil emulsion explosives in which the emulsifier is the reaction product of two components. The first component is the reaction product certain carboxylic acids or anhydrides, including substituted succinic acids and anhydrides with ammonia or an amine and an alkali metal or an alkaline earth metal. The second component is the salt of a phosphorous containing acid.
European Patent application EP 561,600 A discloses a water-in-oil emulsion explosive in which the emulsifier is the reaction product of a substituted succinic acylating agent, having at least 1.3 succinic groups per equivalent weight of substituents, with ammonia and/or an amine. The substituent is a polyalkene having an number average molecular weight of greater than 500 and preferably 1300-1500.
Canadian Patent 2,007,348 discloses a water-in-oil emulsion explosive composition containing an expanded perlite as a void former. The invention is operative with explosive emulsions formed using a wide variety of emulsifiers including derivatives of polyisobutenyl succinic anhydride.
U.S. Pat. No. 4,940,497 discloses a water-in-oil emulsion explosive composition containing an expanded perlite as a void former. The invention is operative with explosive emulsions formed using a wide variety of emulsifiers including salts of polyisobutenyl succinic anhydride.
U.S. Pat. No. 4,919,179 discloses a water-in-oil emulsion explosive wherein the emulsifier is a particular type of ester of polyisobutenyl succinic anhydride.
U.S. Pat. No. 4,844,756 discloses a water-in-oil emulsion explosive wherein the emulsifier is a salt produced by reacting a hydrocarbyl substituted carboxylic acid or anhydride, including substituted succinic acids and anhydrides, with ammonia, an amine, and/or an alkali or alkaline earth metal.
U.S. Pat. No. 4,818,309 discloses a water-in-oil emulsion explosive wherein the emulsifier is a polyalkenyl succinic acid or derivative thereof. The succinic acid may be used in the form of an anhydride, an ester, an amide or an imide. A condensate with ethanolamine is preferred.
U.S. Pat. No. 4,708,753 discloses a water-in-oil emulsion suitable for use in explosive and functional fluids wherein the emulsifier is a reaction product of a hydrocarbyl substituted carboxylic acid, including a succinic acid, with an amine. The substituent contains 20-500 carbon atoms, and the aqueous phase contains a water soluble, oil insoluble functional additive.
European Patent EP 102,827 A discloses a water-in-oil emulsion composition useful as a well control fluid. The emulsifier is a polyamine derivative, especially an alkylene polyamine derivative, of a polyisobutenyl succinic anhydride or a borated or carboxylated derivative thereof.
U.S. Pat. No. 4,445,576 discloses a water-in-oil emulsion composition useful as a spacer fluid in well drilling. The emulsifier is an amine derivative, especially a polyamine derivative, of a polyalkenyl succinic anhydride.
U.S. Pat. No. 4,216,114 discloses the demulsification of water-in-oil emulsions using a polyester derivative prepared by reacting a 9-18 carbon alkyl or alkenyl substituted succinic anhydride with a polyalkylene glycol, and a polyhydric alcohol containing greater than 3 hydroxyl groups.
U.S. Pat. No. 3,269,946 discloses water-in-oil emulsions useful as lubricants or hydraulic fluids. The emulsifier is a substituted succinamide.
U.S. Pat. No. 3,255,108 discloses water-in-oil emulsions useful as lubricants or hydraulic fluids. The emulsifier is a substituted succinic ester.
United States defensive publication T969,003 discloses water-in-oil emulsion fertilizers. These materials are prepared by dissolving an invert emulsifier in an oil such as kerosene. The amount of surfactant used can vary over a wide range. The desired release rates are obtained when the surfactant makes up between 0.6 and 1% of the fertilizer formulation. A liquid fertilizer (a water solution) is emulsified with the oil to form an invert emulsion containing 80-90% liquid fertilizer, 10-20% oil and 0.6-1% surfactant. Ammonium phosphate, ammonium polyphosphate, ammonium nitrate, potassium chloride, urea solutions and mixtures thereof may be used as liquid fertilizers.
Patent Application WO93/16968 discloses a method of transport and storage of fertilizer compositions. The nutrient component of the fertilizer composition is in the form of the discontinuous water phase of a water-in-oil emulsion. The volume phase ratio of the discontinuous water phase to the total volume is in the range of 0.85-0.95. The nutrient component may include urea, ammonium nitrate or calcium ammonium nitrate. The emulsifier is added to the oil phase prior to stirring together the aqueous phase and the oil phase.
British Patent Application 0557568A1 discloses fertilizer compositions comprising dispersions or solution of nutrient components and the method for its manufacture. The solution/dispersion constitutes the discontinuous phase of a water-in-oil emulsion having a volume phase ratio of the discontinuous phase to the total volume in the range of 0.80-0.95. The oil or hydrocarbon component of the water-in-oil emulsion comprises mineral vegetable or animal oils, wax or a mixture of these, and the emulsion comprises at least one water-in-oil emulsifier. The oil phase may include an elastomer. The emulsifier disclosed in the examples is sorbitan monooleate (Span 80 from ICI).